The HICS core network

(You don’t need to know anything of what follows but it may be of interest to anyone who wants to understand a bit more of the technical background to the HICS service.)

Here’s the diagram of the HICS core network showing all of the local exchanges which have been “unbundled” by Updata.  An unbundled exchange is one where Updata have installed their own CISCO router, copper to fibre interface (known as a dslam) and UPS.  Updata manage this core network, shown below, on behalf of Hertfordshire County Council.  (Sorry … the diagram below is detailed … but if you click on it you should see it more clearly.)

The HICS Core Network

This core network comprises 100 Mbps, 1 Gbps and 10 Gbps circuits.  The diagram above is a snapshot taken from the SolarWinds network monitoring system.  It was taken during summer holidays so it’s not showing much traffic flow.

Individual schools are connected by tail circuits into their local exchange.  These tail circuits are mostly provided by BT but many secondary schools are connected by Virgin Media fibre circuits.

Also shown on the diagram are the HCC keys sites … County Hall and the Stevenage campus (Farnham and Robertson Houses)  The reason they are shown twice is that there is a resilient pair of routers at those sites.

In the bottom left corner the two data centres are shown … LD4  and LD5.  These are physically located at separate sites in Slough and work as a resilient pair.  In normal operation they share the load but should there be a failure either of them is capable of supporting the network alone.   In normal operation your school will be routed through one data centre but should there be a failure in that data centre your routing will be switched to the other … this may cause a loss of service but for a couple of minutes only.

The IP addresses are found here.

The resilience of the data centres is increased by using two different Internet suppliers.  At LD4 Internet connectivity is supplied through Cogent and at LD5 it’s Level3.

Both data centres host the key services such as proxy servers, DNS servers, Netsweeper web filtering and VPN servers.

1 Response to The HICS core network

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